The present invention relates to rapid wake up fuser systems, and more specifically, to silicone materials useful as layers for rapid wake up fuser systems in electrostatographic, including digital, systems. In embodiments, the layers provide for the warming up period for the fuser member to be significantly decreased, and the power consumption of the fuser member to be decreased, while allowing for high operating temperature and mechanical strength. Also, in embodiments, the layers permit a decrease in contamination of other xerographic components such as photoconductors. In addition, in embodiments, the layers have a low surface energy and the conformity of the layers is not adversely affected.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support which may be the photosensitive member itself or other support sheet such as plain paper.
Most current fusers use conduction as the main heat transfer mechanism to melt toner to paper. Such systems suffer from non-uniform axial temperature distributions when various paper widths are fed through the fusing nip. Some of these problems are addressed through shaping of the heat lamp axial profile or by using multiple heat lamps to allow control of the axial heating profile.
Because axial heat transfer is controlled by conduction, most fusers have difficulty with transport of energy in the axial direction. Invariably, this leads to overheating of the rubber layers which is a major cause for reduced fuser life.
Known heat fixing apparatuses also demonstrate problems due to the lengthy warm up time required before the heating body is raised to a specified temperature. In some machines, the fuser member is in heated mode 90 to 100 percent of the time the machine is turned on. Because the fuser is heated at all times, there is an increased chance of overheating, and mechanical problems resulting from the fuser member overheating or breaking down from overuse.
Moreover, with the fuser member continuously being heated, much energy is wasted. The Environmental Protection Agency has proposed new "energy star" guidelines for printers and copiers. Current fusers that operate in a continuous heat mode may not meet the expectations of a "green machine."
A preferred fusing system for copying and printing is the use of a "rapid wake up" fuser system, wherein the image on a copy substrate is fused by positioning the paper through a nip between a fuser roll and a pressure roll, the fuser roll and/or pressure roll comprising a substrate, a heat transmissive layer and a toner releasing layer (or heat transporting layer). The fuser converts electric energy directly to thermal energy, and is therefore more energy efficient. The rapid wake up fuser member is advantageous in that the warming up period is reduced as the heater is quick to respond. In addition, the rapid wake up fuser member allows for a reduction in energy consumption because the heater is off when the machine is not copying.
Rapid wake up fusing systems as set forth above are well known and disclosed in, for example, U.S. Pat. No. 5,602,635, to Domoto et al., the disclosure of which is hereby incorporated by reference in its entirety. This reference discloses an rapid wake up fusing system including a heated transparent fusing member, the fusing member heated so that the heat energy is focused in a relatively narrow area adjacent the nip, and a heat leveling member in contact with the fusing member, wherein the heat leveling member is adapted to transfer heat along a longitudinal axis of the fusing member so as to equalize the temperature therealong. This fuser member provides a very uniform fusing temperature along its axis and a high efficiency for fusing images to a copy substrate.
Radiant fusers can be rapid turn on because the energy from the lamp is deposited directly into the toner layer raising its temperature to that required for fusing to the paper. However, because the heat is raised to such a high level in a shorter period of time, offset of the toner particles from the support to the fuser member take place during operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there.
Therefore, there exists a specific need for a fusing system member which is quick to heat up, and which allows for decreased use of energy. In addition, there exists a need for a fuser member in which the conformability, a low surface energy and mechanical properties of the release layer are not affected by the configuration of the layers. There further exists a need for a fusing system which provides for good release properties and a decrease in the occurrence of hot offset.